Substituent Effect on the Competition between Hetero-Diels-Alder and Cheletropic Additions of Sulfur Dioxide to 1-Substituted Buta-1,3-dienes
作者:Elena Roversi、Frédéric Monnat、Pierre Vogel、Kurt Schenk、Pietro Roversi
DOI:10.1002/1522-2675(200203)85:3<733::aid-hlca733>3.0.co;2-u
日期:2002.3
The reactivity of sulfur dioxide toward variously substituted butadienes was explored in an effort to define the factors affecting the competition between the hetero-Diels-Alder and cheletropic additions. At low temperature (< -70degrees), 1-alkyl-substituted 1,3-dienes 1 that can adopt s-cis-conformations add to SO2 in the hetero-Diels-Alder mode in the presence of CF3COOH as promoter. In the case
探索了二氧化硫对各种取代的丁二烯的反应性,以试图确定影响杂-Diels-Alder 和螯合添加剂之间竞争的因素。在低温(<-70℃)下,在CF3COOH作为促进剂存在下,1-烷基取代的1,3-二烯1可以采用s-cis-构象以hetero-Diels-Alder模式添加到SO2上。在 (E)-1-亚乙基-2-亚甲基环己烷 ((E)-4a) 的情况下,SO2 的 [4 + 2] 环加成反应在 -90 度快速,无需酸催化剂。(E)-1-(Acyloxy)buta-1,3-dienes (E)-1c、(E)-1y 和 (E)-1z 分别具有 AcO、BzO 和萘-2-(羰氧基) 取代基也在低温下与 SO2 + CF3COOH 进行异质-Diels-Alder 加成,得到相应的 cis- 和 traps-6-(acyloxy)sultines c-2c,y,z 和 t-2c,y 的 1:10 混合物